title: Bimodal electric tissue ablation (BETA)--effect of reversing the polarity of the direct current on the size of ablation.
abstract: BACKGROUND
  Bimodal electric tissue ablation (BETA) is a new technique that uses the direct current in electrolysis to improve the efficacy of radio frequency (RF) ablation. It was hypothesized that attaching the cathode of the electrolytic circuit to the RF electrode will increase the tissue hydration, therefore delaying tissue desiccation during ablation. Consequently, the ablation process can continue for a longer period of time and produce larger ablations. This hypothesis was tested by reversing the polarity of the electrolytic circuit, which theoretically would cause tissue desiccation and therefore produce smaller ablations. This new setup is called reversed polarity bimodal electric ablation (RP-BEA).
  
  
  METHODS
  Three types of ablations standard radiofrequency ablation (RFA), BETA, and RP-BEA) were tested in a pig liver model. In BETA and RP-BEA, 9 V of direct current were provided for 10 min, after which the rf generator were switched on and both electrical circuits allowed to run concurrently. In all three setups, ablations were continued until "roll-off." The size of ablation was measured and compared with each other.
  
  
  RESULTS
  The duration of ablation was significantly shorted in RP-BEA compared with standard RFA and BETA (48 s verus 148 s and 84 s, respectively, P = 0.004). The sizes of ablations in RP-BEA were also significantly smaller compared with standard RFA and BETA-skin.
  
  
  CONCLUSIONS
  RP-BEA caused tissue desiccation resulting in a shorter duration of ablation and smaller ablations. Therefore, the theory that BETA increases ablation size due to the effects of increased tissue hydration around the rf electrode is correct.
authors.affiliation: Department of Surgery, The Queen Elizabeth Hospital, Adelaide, Australia.
authors.forename: Leong U
authors.initials: LU
authors.lastname: Tiong
authors.forename: John W
authors.initials: JW
authors.lastname: Finnie
authors.forename: John B
authors.initials: JB
authors.lastname: Field
authors.forename: Guy J
authors.initials: GJ
authors.lastname: Maddern
mesh_terms: D055011:Ablation Techniques; D000818:Animals; D004572:Electrolysis; D005260:Female; D008099:Liver / Q000601:surgery*; D013552:Swine